This dataset shows the altitude at which the water level would have risen in tightly cased wells and represents conditions during the period from November 2014 through January 2015. Water levels were measured during this period to ensure that wells had adequate time to recover from previous summer pumping and prior to the start of the 2015 summer pumping season. Groundwater-level data from 178 wells cased completely in and open to the Ozark aquifer are available from the USGS National Water Information System (NWIS; data available at http://water.data.usgs.gov/nwis). Groundwater wells were determined to be completed within Ozark aquifer geologic units by evaluating lithology from geophysical logs, groundwater driller logs, total depth, casing depth, publications, and available historical groundwater-level data.